Semiconductor device allowing metal layer routing formed directly under metal pad

ABSTRACT

A semiconductor device may include a metal pad and a first specific metal layer routing. The metal pad is positioned on a first metal layer of the semiconductor device and is directly contacting the first metal layer. The first specific metal layer routing is formed on a second metal layer of the semiconductor device and under the metal pad. In addition, the semiconductor device may include at least one via plug for connecting the first specific metal layer routing to at least one metal region in the first metal layer, where the aforementioned at least one via plug is formed directly under the metal pad.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application and claims the benefit ofU.S. Non-provisional application Ser. No. 15/164,889, which was filed onMay 26, 2016, and is included herein by reference. The U.S.Non-provisional application Ser. No. 15/164,889 claims the benefit ofU.S. Provisional Application No. 62/204,160, which was filed on Aug. 12,2015. In addition, the U.S. Non-provisional application Ser. No.15/164,889 is a continuation in part application and claims the benefitof U.S. Non-provisional application Ser. No. 14/165,594, now U.S. Pat.No. 9,455,226 B2, which was filed on Jan. 28, 2014. The U.S.Non-provisional application Ser. No. 14/165,594 claims the benefit ofU.S. Provisional Application No. 61/759,497, which was filed on Feb. 1,2013.

BACKGROUND

The disclosed embodiments of the present invention relate to asemiconductor device, and more particularly, to a semiconductor devicewhich can allow a metal layer routing formed directly under a metal pad.

Please refer to FIG. 1. FIG. 1 is a simplified top-view diagram of aconventional semiconductor device 100, wherein the semiconductor device100 can be a chip. As shown in FIG. 1, the semiconductor device 100comprises: a metal pad 102, a power line 104, and a ground line 106.However, the power line 104 and a ground line 106 can not be formedunder the metal pad 102, and thus the semiconductor device 100 has aproblem of requiring a large layout area for the power line 104 and aground line 106.

SUMMARY

In accordance with exemplary embodiments of the present invention, asemiconductor device is proposed to solve the above-mentioned problem.

According to an aspect of the present invention, an exemplarysemiconductor device is disclosed. The semiconductor device comprises: ametal pad and a first specific metal layer routing. The metal pad ispositioned on a first metal layer of the semiconductor device. The firstspecific metal layer routing is formed on a second metal layer of thesemiconductor device, and directly under the metal pad.

According to an aspect of the present invention, an exemplarysemiconductor device is disclosed. The semiconductor device may comprisea metal pad and a first specific metal layer routing. The metal pad ispositioned on a first metal layer of the semiconductor device and isdirectly contacting the first metal layer. The first specific metallayer routing is formed on a second metal layer of the semiconductordevice and under the metal pad. In addition, the semiconductor devicemay comprise at least one via plug (e.g. one or more via plugs, such asa plurality of via plugs) for connecting the first specific metal layerrouting to at least one metal region (e.g. one or more metal regions) inthe first metal layer, where the aforementioned at least one via plug isformed directly under the metal pad.

According to an aspect of the present invention, an exemplarysemiconductor device is disclosed. The semiconductor device may comprisea metal pad and a first specific metal layer routing. The metal pad ispositioned in a first metal layer of the semiconductor device. The firstspecific metal layer routing is formed in a second metal layer of thesemiconductor device and under the metal pad. In addition, thesemiconductor device may comprise at least one via plug (e.g. one ormore via plugs, such as a plurality of via plugs) for connecting thefirst specific metal layer routing to at least one metal region (e.g.one or more metal regions) in the first metal layer, where theaforementioned at least one via plug is formed directly under the metalpad.

According to an aspect of the present invention, an exemplarysemiconductor device is disclosed. The semiconductor device may comprisea metal pad, and comprise a first specific metal layer routing and asecond specific metal layer routing. The metal pad is positioned in afirst metal layer of the semiconductor device. The first specific metallayer routing and the second specific metal layer routing are formed ina second metal layer of the semiconductor device. In addition, thesemiconductor device may comprise at least one via plug (e.g. one ormore via plugs, such as a plurality of via plugs) for connecting thefirst specific metal layer routing to at least one metal region (e.g.one or more metal regions) in the first metal layer, where the firstspecific metal layer routing is directly under the metal pad and thesecond specific metal layer routing is not directly positioned under themetal pad.

According to an aspect of the present invention, an exemplarysemiconductor device is disclosed. The semiconductor device may comprisea metal pad and a first specific metal layer routing. The metal pad ispositioned in a first metal layer of the semiconductor device. The firstspecific metal layer routing is formed in a second metal layer of thesemiconductor device and under the metal pad. In addition, thesemiconductor device may comprise at least one via plug (e.g. one ormore via plugs, such as a plurality of via plugs) for connecting thefirst specific metal layer routing to at least one metal region (e.g.one or more metal regions) in the first metal layer.

Briefly summarized, compared with prior art, since the semiconductordevice disclosed by the present invention can allow a metal layerrouting formed directly under a metal pad, the layout area size of thesemiconductor device can be reduced effectively.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified top-view diagram of a conventional semiconductordevice.

FIG. 2 is a simplified cross-sectional diagram of a semiconductor deviceaccording to a first exemplary embodiment of the present invention.

FIG. 3 is a simplified top-view diagram of the semiconductor device inFIG. 2.

FIG. 4 is a simplified cross-sectional diagram of a semiconductor deviceaccording to a second exemplary embodiment of the present invention.

FIG. 5 is a simplified top-view diagram of the semiconductor device inFIG. 4.

FIG. 6 is a simplified cross-sectional diagram of a semiconductor deviceaccording to a third exemplary embodiment of the present invention.

FIG. 7 is a simplified top-view diagram of the semiconductor device inFIG. 6.

FIG. 8 is a simplified top-view diagram of a semiconductor deviceaccording to a fourth exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Certain terms are used throughout the description and following claimsto refer to particular components. As one skilled in the art willappreciate, manufacturers may refer to a component by different names.This document does not intend to distinguish between components thatdiffer in name but not function. In the following description and in theclaims, the terms “include” and “comprise” are used in an open-endedfashion, and thus should be interpreted to mean “include, but notlimited to . . . ”.

Please refer to FIG. 2 and FIG. 3. FIG. 2 is a simplifiedcross-sectional diagram of a semiconductor device 200 according to afirst exemplary embodiment of the present invention, and FIG. 3 is asimplified top-view diagram of the semiconductor device 200, where thesemiconductor device 200 can be a chip. As shown in FIG. 2 and FIG. 3,the semiconductor device 200 may comprise a metal pad 202, a firstspecific metal layer routing 204, and a second specific metal layerrouting 205. The metal pad 202 is positioned on a first metal layer 206of the semiconductor device 200, where the metal pad 202 has a thicknesssmaller than 20 KA (i.e. 2 micrometers), and material of the metal pad202 can be aluminum. The first specific metal layer routing 204 isformed on a second metal layer 208 of the semiconductor device 200, anddirectly under the metal pad 202. As shown in FIG. 2, the metal pad 202may be regarded as a portion of the first metal layer 206, and the firstspecific metal layer routing 204 and the second specific metal layerrouting 205 may be regarded as some portions of the second metal layer208. In addition, please note that the above embodiment is only for anillustrative purpose and is not meant to be a limitation of the presentinvention. For example, the architecture shown in FIG. 2 can be changedaccording to different design requirements.

The first specific metal layer routing 204 has a uniform pattern, wherethe uniform pattern has a metal density range between 30% and 70%.Please note that if the metal density of the uniform pattern is higherthan 70%, the first specific metal layer routing 204 under the metal pad202 will fail. If the metal density of the uniform pattern is lower than30%, it will be hard to design the first specific metal layer routing204 under the metal pad 202. As shown in FIG. 3, the first specificmetal layer routing 204 may comprise four first power lines 210, fourfirst ground lines 212, and at least one unused metal line (e.g. one ormore unused metal lines) such as the unused metal line 214 of thisembodiment, where there are oxide regions 216 between the first powerlines 210, the first ground lines 212, and the unused metal line 214,and each oxide region 216 can have a width greater than 2 micrometers.In addition, the unused metal line 214 is kept as a dummy pattern forrobust bondability. The second specific metal layer routing 205 isformed on the second metal layer 208 of the semiconductor device 200 andconnected to the first specific metal layer routing 204, where thesecond specific metal layer routing 205 is not positioned under themetal pad 202. The second specific metal layer routing 205 may comprisea second power line 218 and a second ground line 220. Please note thatthe first metal layer 206 and the second metal layer 208 are adjacentmetal layers of the semiconductor device 200, and there is an oxidelayer 209 between the first metal layer 206 and the second metal layer208. In addition, please note that the above embodiment is only for anillustrative purpose and is not meant to be a limitation of the presentinvention. For example, the numbers of the first power lines 210, thefirst ground lines 212, and the unused metal line 214 can be changedaccording to different design requirements, respectively.

Briefly summarized, compared with prior art, since the semiconductordevice disclosed by the present invention can allow the metal layerrouting formed directly under the metal pad, the layout area size of thesemiconductor device can be reduced effectively.

Please refer to FIG. 4 and FIG. 5. FIG. 4 is a simplifiedcross-sectional diagram of a semiconductor device 300 according to asecond exemplary embodiment of the present invention, and FIG. 5 is asimplified top-view diagram of the semiconductor device 300, where thesemiconductor device 300 can be a chip. As shown in FIG. 4 and FIG. 5,the semiconductor device 300 may comprise a metal pad 302, a firstspecific metal layer routing 304, and a second specific metal layerrouting 305. The metal pad 302 is positioned on a first metal layer 306of the semiconductor device 300, where the metal pad 302 has a thicknesssmaller than 20 KA (i.e. 2 micrometers), and material of the metal pad302 can be aluminum. The first specific metal layer routing 304 isformed on a second metal layer 308 of the semiconductor device 300, anddirectly under the metal pad 302. As shown in FIG. 4, the metal pad 302may be regarded as a portion of the first metal layer 306, and the firstspecific metal layer routing 304 and the second specific metal layerrouting 305 may be regarded as some portions of the second metal layer308. In addition, please note that the above embodiment is only for anillustrative purpose and is not meant to be a limitation of the presentinvention. For example, the architecture shown in FIG. 4 can be changedaccording to different design requirements.

The first specific metal layer routing 304 has a uniform pattern, wherethe uniform pattern has a metal density range between 30% and 70%.Please note that if the metal density of the uniform pattern is higherthan 70%, the first specific metal layer routing 304 under the metal pad302 will fail. If the metal density of the uniform pattern is lower than30%, it will be hard to design the first specific metal layer routing304 under the metal pad 302. As shown in FIG. 5, the first specificmetal layer routing 304 may comprise four first IO routing lines 310 andfive unused metal lines 314, where there are oxide regions 316 betweenthe first IO routing lines 310 and the unused metal lines 314, and eachoxide region 316 can have a width greater than 3 micrometers. Inaddition, the unused metal lines 314 are kept as a dummy pattern forrobust bondability. The second specific metal layer routing 305 isformed on the second metal layer 308 of the semiconductor device 300 andconnected to the first specific metal layer routing 304, where thesecond specific metal layer routing 305 is not positioned under themetal pad 302. The second specific metal layer routing 305 may comprisefour second IO routing lines 318, where the semiconductor device 300 maycomprise at least one via plug (e.g. one or more via plugs) forconnecting at least one portion (e.g. a portion or all) of the second IOrouting lines 318 to other metal line(s) in other metal layer(s), suchas a plurality of via plugs for connecting the second IO routing lines318 to some other metal lines in one or more other metal layers,respectively. Please note that the first metal layer 306 and the secondmetal layer 308 are adjacent metal layers of the semiconductor device300, and there is an oxide layer 309 between the first metal layer 306and the second metal layer 308. In addition, please note that the aboveembodiment is only for an illustrative purpose and is not meant to be alimitation of the present invention. For example, the numbers of thefirst IO routing lines 310 and the unused metal lines 314 can be changedaccording to different design requirements, respectively.

Briefly summarized, compared with prior art, since the semiconductordevice disclosed by the present invention can allow the metal layerrouting formed directly under the metal pad, the layout area size of thesemiconductor device can be reduced effectively.

Please refer to FIG. 6 and FIG. 7. FIG. 6 is a simplifiedcross-sectional diagram of a semiconductor device 400 according to athird exemplary embodiment of the present invention, and FIG. 7 is asimplified top-view diagram of the semiconductor device 400, where thesemiconductor device 400 can be a chip. As shown in FIG. 6 and FIG. 7,the semiconductor device 400 may comprise a metal pad 402, a firstspecific metal layer routing 404, and a second specific metal layerrouting 405. The metal pad 402 is positioned on a first metal layer 406of the semiconductor device 400, where the metal pad 402 has a thicknesssmaller than 20 KA (i.e. 2 micrometers), and material of the metal pad402 can be aluminum. The first specific metal layer routing 404 isformed on a second metal layer 408 of the semiconductor device 400 andunder the metal pad 402. As shown in FIG. 6, the metal pad 402 may beregarded as a portion of the first metal layer 406, and the firstspecific metal layer routing 404 and the second specific metal layerrouting 405 may be regarded as some portions of the second metal layer408. In addition, the semiconductor device 400 may comprise at least onevia plug (e.g. one or more via plugs) for connecting the first specificmetal layer routing 404 to at least one metal region (e.g. one or moremetal regions) in the first metal layer 406, where the aforementioned atleast one via plug is formed directly under the metal pad 402. Forexample, the aforementioned at least one via plug may comprise multiplevia plugs, such as a plurality of via plugs 401, directly under themetal pad 402, and the via plugs 401 may be utilized for connectingmultiple portions of the first specific metal layer routing 404 to somemetal regions in the first metal layer 406, respectively. Please notethat the above embodiment is only for an illustrative purpose and is notmeant to be a limitation of the present invention. For example, thearchitecture shown in FIG. 6 can be changed according to differentdesign requirements. In some examples, the numbers of the via plugs 401can be changed according to different design requirements.

The first specific metal layer routing 404 has a uniform pattern, wherethe uniform pattern has a metal density range between 30% and 70%.Please note that if the metal density of the uniform pattern is higherthan 70%, the first specific metal layer routing 404 under the metal pad402 will fail. If the metal density of the uniform pattern is lower than30%, it will be hard to design the first specific metal layer routing404 under the metal pad 402. As shown in FIG. 7, the first specificmetal layer routing 404 may comprise a plurality of sets of terminallines corresponding to terminals of a plurality of field effecttransistors (FETs), respectively, such as the set of terminal lines{410-1, 414-1} and the set of terminal lines {410-2, 414-2}. Forexample, the terminal line 410-1 can be a source terminal linecorresponding to the source terminal of a first FET within the pluralityof FETs, and the terminal line 414-1 can be a drain terminal linecorresponding to the drain terminal of the first FET. In addition, theterminal line 410-2 can be a source terminal line corresponding to thesource terminal of a second FET within the plurality of FETs, and theterminal line 414-2 can be a drain terminal line corresponding to thedrain terminal of the second FET. In some embodiments, the arrangementof the plurality of sets of terminal lines may vary. For example, theterminal line 414-1 can be a source terminal line corresponding to thesource terminal of the first FET within the plurality of FETs, and theterminal line 410-1 can be a drain terminal line corresponding to thedrain terminal of the first FET. In addition, the terminal line 414-2can be a source terminal line corresponding to the source terminal ofthe second FET within the plurality of FETs, and the terminal line 410-2can be a drain terminal line corresponding to the drain terminal of thesecond FET.

According to the embodiment shown in FIG. 7, the small boxes illustratedwith dashed lines can be taken as examples of the via plugs 401, and thevia plugs 401 may be positioned between the metal pad 402 and theplurality of sets of terminal lines (e.g. the set of terminal lines{410-1, 414-1} and the set of terminal lines {410-2, 414-2}). As shownin FIG. 7, there may be at least one oxide region (e.g. one or moreoxide regions) between the plurality of sets of terminal lines, such asthe oxide regions 416 between the set of terminal lines {410-1, 414-1}and the set of terminal lines {410-2, 414-2} in this embodiment, andeach oxide region of the aforementioned at least one oxide region, suchas the oxide region 416 has a width greater than 2 micrometers. Forexample, there is an oxide region 412 between the source terminal lineand the drain terminal line of each set of the plurality of sets ofterminal lines, and the oxide region 412 has a width greater than 2micrometers. In addition, the second specific metal layer routing 405 isformed on the second metal layer 408 of the semiconductor device 400 andconnected to the first specific metal layer routing 404, where thesecond specific metal layer routing 405 is not positioned under themetal pad 402. The second specific metal layer routing 405 may comprisea plurality of sets of terminal lines corresponding to the plurality ofsets of terminal lines of the first specific metal layer routing 404,respectively. Examples of the plurality of sets of terminal lines of thesecond specific metal layer routing 405 may include, but not limited to,the set of terminal lines {420-1, 424-1}, the set of terminal lines{420-2, 424-2}, the set of terminal lines {430-1, 434-1}, and the set ofterminal lines {430-2, 434-2}. In this embodiment, the plurality of setsof terminal lines of the second specific metal layer routing 405 may beregarded as extensions of the plurality of sets of terminal lines of thefirst specific metal layer routing 404, respectively, where the width ofthe terminal lines, the width of the gap between adjacent sets ofterminal lines, and the width of the gap between the terminal lines ineach set of terminal lines may be kept constant, no matter whether theterminal lines are under the metal pad 402 or not. Please note that thefirst metal layer 406 and the second metal layer 408 are adjacent metallayers of the semiconductor device 400, and there is an oxide layer 409between the first metal layer 406 and the second metal layer 408. Forexample, the via plugs 401 may pass through the oxide layer 309. Inaddition, please note that the above embodiment is only for anillustrative purpose and is not meant to be a limitation of the presentinvention. For example, the numbers of sets of terminal lines can bechanged according to different design requirements.

Briefly summarized, compared with prior art, since the semiconductordevice disclosed by the present invention can allow the metal layerrouting formed directly under the metal pad, the layout area size of thesemiconductor device can be reduced effectively.

According to some embodiments, at least one size of at least one side ofthe aforementioned at least one via plug (e.g. one or more via plugs,such as the via plugs 401) is not less than 1 micrometer. For example,each of the via plugs 401 may be implemented to have a conduction areasuch as 1 micrometer by 1 micrometer, to allow currents to pass throughthe via plugs 401 (e.g. from the metal pad 402 to the first specificmetal layer routing 404, or from the first specific metal layer routing404 to the metal pad 402) without damaging the via plugs 401, and thenumber of via plugs within the via plugs 401 may be very great, toachieve a predetermined percentage of the area under the metal pad 402,where they may be widely and uniformly distributed, under the metal pad402. This is only for an illustrative purpose and is not meant to be alimitation of the present invention. According to some embodiments, thesize of a first side of the aforementioned at least one via plug (e.g.one or more via plugs, such as the via plugs 401) is not less than 1micrometer, and the size of a second side of the aforementioned at leastone via plug (e.g. one or more via plugs, such as the via plugs 401) isnot less than 3 micrometers. For example, each of the via plugs 401 maybe implemented to have a conduction area such as 1 micrometer by 3micrometers, to allow currents to pass through the via plugs 401 (e.g.from the metal pad 402 to the first specific metal layer routing 404, orfrom the first specific metal layer routing 404 to the metal pad 402)without damaging the via plugs 401.

According to some embodiments, as the multiple via plugs such as the viaplugs 401 are implemented directly under the metal pad 402, someimplementation parameters regarding the terminal lines may be keptconstant, no matter whether the terminal lines are under the metal pad402 or not. Examples of these implementation parameters regarding theterminal lines may include, but not limited to, the width of theterminal lines, the width of the gap between adjacent sets of terminallines, and the width of the gap between the terminal lines in each setof terminal lines.

FIG. 8 is a simplified top-view diagram of a semiconductor deviceaccording to a fourth exemplary embodiment of the present invention,where the semiconductor device of this embodiment can be taken as anexample of the semiconductor device 400 shown in FIG. 7, and the metalpad 502 can be taken as an example of the metal pad 402 described above.For brevity, the number of sets of terminal lines under the metal pad502 may be two as illustrated in FIG. 7. Please note that the aboveembodiment is only for an illustrative purpose and is not meant to be alimitation of the present invention.

According to this embodiment, the terminal lines S can be taken as anexample of the source terminal line corresponding to the source terminalof one of the FETs, and the terminal lines D can be taken as an exampleof the drain terminal line corresponding to the drain terminal of one ofthe FETs. Please note that the width C of the terminal lines, the widthX of the gap between adjacent sets of terminal lines, and the width B ofthe gap between the terminal lines in each set of terminal lines may bekept constant, no matter whether the terminal lines are under the metalpad 502 or not. In addition, the first specific metal layer routing 404of this embodiment may comprise at least one unused metal line (e.g. oneor more unused metal lines) such as the two unused metal lines havingthe width A. For example, the aforementioned at least one unused metalline such as the two unused metal lines may be kept as a dummy patternfor robust bondability. For brevity, similar descriptions for thisembodiment are not repeated in detail here.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A semiconductor device, comprising: a metal pad,positioned in a first metal layer of the semiconductor device; a firstspecific metal layer routing, formed in a second metal layer of thesemiconductor device and under the metal pad; and at least one via plugfor connecting the first specific metal layer routing to at least onemetal region in the first metal layer, wherein the via plug is formeddirectly under the metal pad.
 2. The semiconductor device of claim 1,wherein the metal pad has a thickness smaller than 20 KA.
 3. Thesemiconductor device of claim 1, wherein material of the metal pad isaluminum.
 4. The semiconductor device of claim 1, wherein the firstspecific metal layer routing has a uniform pattern.
 5. The semiconductordevice of claim 4, wherein the uniform pattern has a metal density rangebetween 30% and 70%.
 6. The semiconductor device of claim 1, wherein thefirst specific metal layer routing comprises a plurality of sets ofterminal lines corresponding to terminals of a plurality of field effecttransistors (FETs), respectively.
 7. The semiconductor device of claim6, wherein there are oxide regions between the plurality of sets ofterminal lines, and each oxide region has a width greater than 2micrometers.
 8. The semiconductor device of claim 6, wherein a set ofterminal lines within the plurality of sets of terminal lines comprisesa source terminal line and a drain terminal line respectivelycorresponding to a source terminal and a drain terminal of a FET withinthe plurality of FETs.
 9. The semiconductor device of claim 8, whereinthere is an oxide region between the source terminal line and the drainterminal line, and the oxide region has a width greater than 2micrometers.
 10. The semiconductor device of claim 1, furthercomprising: a second specific metal layer routing, formed on the secondmetal layer of the semiconductor device and connected to the firstspecific metal layer routing, wherein the second specific metal layerrouting is not directly positioned under the metal pad.
 11. Thesemiconductor device of claim 10, wherein the first specific metal layerrouting comprises a plurality of sets of terminal lines corresponding toterminals of a plurality of field effect transistors (FETs),respectively; and the second specific metal layer routing comprises aplurality of sets of terminal lines corresponding to the plurality ofsets of terminal lines of the first specific metal layer routing,respectively.
 12. The semiconductor device of claim 11, wherein theplurality of sets of terminal lines of the second specific metal layerrouting are extensions of the plurality of sets of terminal lines of thefirst specific metal layer routing, respectively.
 13. The semiconductordevice of claim 1, wherein the semiconductor device is a chip.
 14. Thesemiconductor device of claim 1, wherein the first metal layer and thesecond metal layer are adjacent metal layers of the semiconductordevice.
 15. The semiconductor device of claim 1, wherein at least onesize of at least one side of the at least one via plug is not less than1 micrometer.
 16. The semiconductor device of claim 15, wherein a sizeof a first side of the at least one via plug is not less than 1micrometer, and a size of a second side of the at least one via plug isnot less than 3 micrometers.
 17. The semiconductor device of claim 1,wherein the at least one via plug comprises multiple via plugs, directlyunder the metal pad.
 18. A semiconductor device, comprising: a metalpad, positioned in a first metal layer of the semiconductor device; afirst specific metal layer routing and a second specific metal layerrouting, formed in a second metal layer of the semiconductor device; andat least one via plug for connecting the first specific metal layerrouting to at least one metal region in the first metal layer, whereinthe first specific metal layer routing is directly under the metal padand the second specific metal layer routing is not directly positionedunder the metal pad.
 19. The semiconductor device of claim 18, whereinthe via plug is formed directly under the metal pad.
 20. A semiconductordevice, comprising: a metal pad, positioned in a first metal layer ofthe semiconductor device; a first specific metal layer routing, formedin a second metal layer of the semiconductor device and under the metalpad; and at least one via plug for connecting the first specific metallayer routing to at least one metal region in the first metal layer.